JP4501824B2 - Color adjustment of color image data - Google Patents

Description

  The present invention relates to a technique for adjusting the color of color image data output by an output device.

  As representative color modes for expressing and reproducing colors, there are RGB and CMY. An example of an output device that reproduces colors using RGB is a color display, and an example of an output device that reproduces colors using CMY is a color printer. Since the color reproducibility in these output devices depends on the characteristics of the device, the target color cannot always be reproduced. For this reason, it is necessary to perform color correction of the image, but this color correction is basically based on gray balance. Conventionally, as a technique for adjusting the gray balance, various techniques such as a technique for obtaining an appropriate blending ratio of C, M, and Y (or R, G, and B) have been proposed (see, for example, Patent Document 1). .

Japanese Patent Laid-Open No. 08-289162

  However, in the above prior art, the compounding ratio of C, M, Y (or R, G, B) is directly specified, so that it is difficult to adjust the gray balance with high accuracy. was there. This is because the mixing ratio of C, M, and Y (or R, G, and B) is slightly different from the proper value, and the brightness (luminance) is changed to make the color itself completely different from gray. Therefore, it was difficult to adjust the gray balance with high accuracy.

  The problem to be solved by the present invention is to make it possible to adjust color balance such as gray balance with high accuracy and ease.

  As means for solving at least a part of the problems described above, the following configuration is adopted.

The color adjusting device of the present invention is
A color adjustment device for adjusting the color of color image data output from an output device,
Image data input means for inputting target image data in which the color of a pixel is expressed by a first parameter representing brightness and second and third parameters relating to color;
Adjustment amount designating means for designating respective adjustment amounts of the second and third parameters for each value of the first parameter according to an instruction from an operator;
Image data correction means for correcting the target image data in accordance with the designated adjustment amount;
Image data output means for converting the target image data corrected by the image data correction means into color image data expressed by a color space reproducible by the output device and sending the color image data to the output device. Yes.

  According to the color adjustment apparatus having the above configuration, the target image data is input in a data format in which the color of the pixel is expressed by the first parameter representing brightness and the second and third parameters related to color. The respective adjustment amounts of the second and third parameters for each value of the first parameter are designated in accordance with instructions from the operator. Then, the target data is corrected according to the designated adjustment amount. Therefore, the operator can adjust the color balance to the desired color without changing the brightness of the target image data. Therefore, according to the color adjusting apparatus of the present invention, it is possible to easily and accurately adjust a color balance such as a gray balance.

  The target image data includes luminance L as the first parameter, chromaticity a from green to red as the second parameter, and chromaticity b from blue to yellow as the third parameter. It is also possible to use Lab-format color image data in which the color of the pixel is expressed. In addition, L, a, and b are accurately expressed as L *, a *, and b * with “*” after each component. However, in this specification, “*” is omitted for simplicity. Yes.

  According to the above configuration, since the chromaticities a and b corresponding to the psychological four primary colors of a person can be changed, the operator can change the target image data so as to increase red or blue. In contrast, the intended color can be easily given. As a result, the color balance can be adjusted with higher accuracy.

  The target image data may be color image data in YCrCb format in which pixel colors are expressed by brightness Y as the first parameter and color differences Cr and Cb as the second and third parameters. Also with this configuration, the color balance can be adjusted with higher accuracy.

  The adjustment amount designation means takes the first parameter on one of the horizontal axis and the vertical axis, and takes the respective adjustment amounts of the second and third parameters on the other axis. Display control means for displaying on the display device a graph representing the relationship between the parameters of the first parameter and the respective adjustment amounts of the second and third parameters, and an instruction from the operator for the displayed graph is received and shown in the graph. It is good also as a structure provided with the graph change means to change the relationship between the 1st parameter to be adjusted and each adjustment amount of a 2nd, 3rd parameter according to the instruction | indication from an operator. According to this configuration, since the operator only has to give an instruction to the graph, the operability is excellent, and the color balance can be adjusted more easily.

  Further, the adjustment amount designation means includes a storage means for storing in advance a plurality of types of parameter association data indicating the relationship between the first parameter and the adjustment amounts of the second and third parameters, and the storage means And selecting means for designating the adjustment amount by selecting one of the plurality of types of parameter correlation data stored in the above based on an instruction from the operator. According to this configuration, since the operator can specify the adjustment amount simply by selecting the parameter correlation data, the operator is excellent in operability, and the color balance can be adjusted more easily. .

  In the configuration in which designation of the adjustment amount is facilitated, the adjustment amount designation means further reads the plurality of types of parameter correlation data from the storage means and displays a plurality of graphs respectively representing each parameter correlation data Display control means for displaying on the apparatus, and the selection means corresponds to the selected graph and a graph selection means for selecting one of the plurality of types of graphs based on an instruction from an operator; It is good also as a structure provided with the parameter correlation data selection means which selects the said parameter correlation data. According to this configuration, since the operator only has to select the graph, the operability is further improved.

  The output device may be a color display, and the color image data may be one in which pixel colors are expressed by three primary colors of red, green, and blue. In this configuration, the target image data input means represents original image data input means for inputting original image data in which pixel colors are expressed by the three primary colors of red, green, and blue, and the original image data represents brightness. Original image data conversion using the first parameter and the second and third parameters relating to the color to convert to color image data in which the color of the pixel is expressed and using the converted color image data as the target image data It is good also as a structure provided with a means.

  According to this configuration, it is possible to adjust the color balance of the original image data in which the pixel color is expressed by the three primary colors of red, green, and blue with high accuracy and ease.

The color adjustment method of the present invention includes:
A color adjustment method for adjusting the color of color image data output from an output device,
The target image data in which the color of the pixel is expressed by the first parameter representing brightness and the second and third parameters related to the color is input,
Specify the respective adjustment amounts of the second and third parameters for each value of the first parameter according to instructions from the operator,
The target image data is corrected according to the designated adjustment amount,
The target image data after correction is converted into color image data expressed by a color space reproducible by the output device, and sent to the output device.

The computer program of the present invention is:
A computer program for adjusting the color of color image data output from an output device,
A function of inputting target image data in which the color of a pixel is expressed by a first parameter representing brightness and second and third parameters relating to color;
A function of designating respective adjustment amounts of the second and third parameters for each value of the first parameter according to an instruction from an operator;
A function of correcting the target image data in accordance with the designated adjustment amount;
A computer program for causing a computer to realize a function of converting the corrected target image data into color image data expressed in a color space reproducible by the output device and sending the color image data to the output device.

  The color adjustment method and computer program of the present invention also provide an effect that the adjustment of the color balance such as the gray balance can be accurately and easily performed as in the color adjustment apparatus of the present invention.

  The recording medium of the present invention is characterized by a computer-readable recording medium that records the computer program of the present invention. This recording medium has the same operation and effect as each computer program of the present invention.

  The present invention includes other aspects as follows. The 1st aspect is an aspect as a program supply apparatus which supplies the 1st or 2nd computer program of this invention via a communication path. In the first aspect, the first or second computer program is placed on a server or the like on a computer network, a necessary program is downloaded to a computer via a communication path, and the program is executed. And a device can be realized.

The best mode for carrying out the present invention will be described based on examples. This embodiment will be described in the following order.
1. First embodiment:
A. Device configuration:
B. Computer processing:
B-1. Overall processing:
B-2. Color adjustment processing:
C. Action / effect:
2. Second embodiment:
3. Other embodiments:

1. First embodiment:
A. Device configuration:
FIG. 1 is an explanatory diagram showing a schematic configuration of a computer system to which the first embodiment of the present invention is applied. The computer system of this embodiment mainly includes a personal computer 10 constituting the color adjustment apparatus of the present invention, and includes a display 20, a keyboard 22, and a mouse 24 as its peripheral devices. Furthermore, a digital camera 26, a CD drive 28, and a printer 29 are connected to the personal computer 10.

  The display 20 is a color display that receives RGB color image data in which pixel colors are represented by red (R), green (G), and blue (B). The printer 29 is a color printer that receives CMYK format color image data in which pixel colors are represented by cyan (C), magenta (M), yellow (Y), and black (K). The mouse 24 can be replaced with other pointing devices such as a trackball, a trackpad, and a tablet.

  The personal computer 10 includes a memory 13, a display image memory 14, a hard disk drive 15, an input control unit 16, a display control unit 17, an output control unit 18, and the like that are mutually connected by a bus 12 around a CPU 11 as a central processing unit. Is provided. The memory 13 stores various data and becomes a work area of the CPU 11. The display image memory 14 is a memory that temporarily stores color image data to be displayed on the display 20.

  The hard disk drive 15 stores a computer program Pr as software of the color adjustment device. The hard disk drive 15 stores one or more color image data (hereinafter also simply referred to as “image data”) Dp. The image data Dp is image data of a captured image taken by the digital camera 26 and is stored in a predetermined area (for example, a holder) of the hard disk drive 15. The image data Dp is RGB color image data.

  The input control unit 16 is a control unit that captures input operations from the keyboard 22 and the mouse 24, captures image data from the digital camera 26, and captures data from the CD drive 28. The display control unit 17 is a control unit that controls signal output to the display 20. The output control unit 18 is a control unit that controls printing on the color printer 29.

  The computer program Pr is originally stored in a CD-ROM (not shown) as a recording medium. The computer program Pr can be read from the CD-ROM and installed in the hard disk drive 15 by setting the CD-ROM in the CD drive 28 and starting a predetermined installation program. When the CPU 11 executes this computer program Pr, various structural requirements of the color adjustment apparatus of the present invention are realized.

  In FIG. 1, various constituent requirements are indicated by functional blocks implemented in the CPU 11. That is, the CPU 11 includes an image data input unit 31, an adjustment amount designation unit 32, an image data correction unit 33, and an image data output unit 34 as functions. This computer program Pr is actually an application program for photo retouching that modifies a captured image captured by the digital camera 26, and the functions of the above-described units 31 to 34 are given to the personal computer 10 by some of the modules. make it happen.

  The computer program Pr is provided as a configuration stored in another portable recording medium (portable recording medium) such as a flexible disk, a magneto-optical disk, and an IC card in place of the CD-ROM. It can be. Further, the computer program Pr can be provided via a network from a specific server connected to an external network. The network may be the Internet or a computer program obtained by downloading from a specific homepage. Alternatively, it may be a computer program supplied in the form of an email attachment.

B. Computer processing:
B-1. Overall processing:
When the computer program Pr is started, an application window is first displayed on the display 20. This application window constitutes a graphical user interface (GUI).

  FIG. 2 is an explanatory diagram showing an example of the application window WD. As shown in the figure, in the process menu column MN on the left side of the application window WD, four types of buttons BT1, BT2, BT3, and BT4 of [Input], [Modify], [Print], and [Output] are directed downward. The operator clicks these buttons BT1 to BT4 with the mouse 24 in order, and captures and modifies the captured image captured by the digital camera 26 on the screen of the display 20, and outputs it. Work can be carried out.

  First, the operator clicks the [Input] button BT1 to perform processing for capturing the image data Dp from the hard disk drive 15. Here, instead of the hard disk drive 15, it is possible to change to a configuration for capturing image data directly from the digital camera 26 or a configuration for capturing image data from another storage medium such as a DVD. The captured image data (hereinafter referred to as “original image data”) Dp is displayed in the work field FDW of the application window WD.

  Thereafter, the operator clicks the [Modify] button BT2 to modify the captured original image data Dp. FIG. 2 shows the case where the [Modify] button BT2 is clicked. As shown in the figure, the menu bar MB of the application window WD is provided with buttons such as [File], [Course menu], [Edit], [Display], [Modify], [Repair / Process]. In the figure, a pull-down menu DM that opens when the [Modify] button is clicked is shown. The operator clicks the [Modify] button and clicks a desired option from the pull-down menu DM, whereby “brightness”, “contrast”, “gray balance”, and “rotation” are applied to the original image data Dp. And “trimming” can be performed.

B-2. Color adjustment processing:
The “gray balance” is related to the present invention. The color adjustment process executed when the “Gray balance” option in the pull-down menu DM is clicked will be described in detail below.

  FIG. 3 is a flowchart showing the color adjustment process executed by the CPU 11. When the [Gray balance] option in the pull-down menu DM is clicked and the process is started, the CPU 11 first performs a process of displaying the adjustment amount designation dialog box DB on the display 20 (step S110). This dialog box DB is for inputting an adjustment amount for color adjustment to the computer main body 16 in response to an instruction from the operator.

  FIG. 4 is an explanatory diagram showing an example of the adjustment amount designation dialog box DB. As shown in the figure, the adjustment amount designation dialog box DB displays a graph GH in which the horizontal axis indicates the luminance L and the vertical axis indicates the increase / decrease values as the adjustment amounts of the chromaticities a and b. Here, the luminance L and the chromaticities a and b are three parameters in the Lab color space defined by CIE (1976). That is, the luminance L is a first parameter indicating brightness, the chromaticity a is a second parameter indicating green to red among human psychological four primary colors, and the chromaticity b is It is a third parameter indicating blue to yellow among the four primary colors. The vertical axis of the graph is common to the chromaticities a and b, and indicates the increase / decrease values of the chromaticities a and b, not the values of the chromaticities a and b themselves. The upper part from the center of the vertical axis indicates an increase in chromaticity a (or chromaticity b), that is, a positive amount, and the lower part from the center of the vertical axis indicates a decrease in chromaticity a (or chromaticity b), Indicates a negative amount.

  Two radio buttons RB1 and RB2 are provided at the upper left of the graph GH, the right radio button RB1 corresponds to chromaticity a, and the left radio button RB2 corresponds to chromaticity b. The operator switches the instruction of the radio buttons RB1 and RB2 and then draws a curve on the graph GH, thereby increasing or decreasing the chromaticity for each value of the luminance L between the chromaticity a and the chromaticity b. You can switch between and input.

The operation of drawing a curve on the graph GH is as follows. As shown in FIG. 5, an arbitrary position P1 on the graph GH is designated by a click operation by the operator using the mouse 24, so that the graph GH has a left end (luminance L = 0, color) on the horizontal axis. degree a, and increase and decrease value = point 0) P2 of b, or point P1 is clicked, the right end of the horizontal axis (luminance L = 100, the chromaticity a, point change amount = 0 b) the curve C1 connecting P3 Is drawn. As shown in the figure, when the right radio button RB1 is in the selected state, the curve C1 is for chromaticity a. As a result, the operator increases the chromaticity a for each value of the luminance L (because the curve C1 is above the center of the vertical axis), that is, specifies the amount to increase red according to the curve C1. can do. When the curve C1 is drawn so as to be positioned below the center of the vertical axis, it is possible to specify an amount by which the chromaticity a is reduced, that is, green is strengthened for each value of the luminance L.

On the other hand, as shown in FIG. 6, when the radio button RB2 is selected by the click operation, an arbitrary position P4 on the graph GH is designated by the click operation using the mouse 24, so that the graph GH is displayed. Are the left end (brightness L = 0, increase / decrease value of chromaticity a, b = 0) P2, the clicked point P1, and the right end (brightness L = 100 , chromaticity a, b) on the horizontal axis. curve C2 connecting the increase or decrease value = point 0) P3 is drawn. When the left radio button RB2 is in the selected state, the curve C2 is for chromaticity b. As a result, the operator decreases the chromaticity b with respect to each value of the luminance L (because the curve C2 is lower than the center of the vertical axis), that is, specifies the amount to increase blue according to the curve C2. can do. When the curve C2 is drawn so as to be located above the center of the vertical axis, it is possible to specify an amount for increasing the chromaticity b, that is, increasing yellow for each value of the luminance L.

  In FIG. 6, the curve C1 indicating the increase / decrease value of the chromaticity a is represented by a solid line, and the curve C2 indicating the increase / decrease value of the chromaticity b is represented by an alternate long and short dash line. In practice, the curve C1 is red and the curve C2 is blue. With this configuration, the curves C1 and C2 can be identified even if they are simultaneously displayed on the graph GH. The curve C1 (C2) is drawn so as to smoothly connect (interpolate) the above three points P2, P1, P3 (P2, P4, P3). A curve is adopted. Note that other methods such as a Bezier curve may be used instead of the spline curve. The colors of the curves C1 and C2 do not have to be limited to red and blue, but can be other colors.

  In the operation of drawing a curve on the graph GH described above with reference to FIGS. 5 and 6, the click is performed only once. However, by performing the click a plurality of times, various shapes of curves can be drawn. it can. FIG. 7 is an explanatory diagram illustrating an operation of drawing a curve by clicking a plurality of times. As shown in (a) of the figure, when the point P5 is first clicked, a curve C1a connecting the left end P2 of the horizontal axis and the clicked point P5 to the right end P3 of the horizontal axis is drawn. Thereafter, as shown in (b) in the figure, when the point P6 is clicked, the curve C1a is aligned with the left end P2 of the horizontal axis, the point P6 clicked for the second time, and the point P5 clicked for the first time. It is transformed into a curve C1b connecting the right end P3 of the shaft. Note that the number of clicks is not limited to two, but each time a click is made, the two fixed points P1 and P2 at both ends of the horizontal axis and the clicked points are smoothed. It is transformed into a passing curve. As a result, it can be set as the curve of various shapes.

  In this embodiment, the point where the luminance L is 0 and the point where the value is 100 are configured such that the chromaticities a and b do not take values other than 0. A coordinate position that cannot be taken is configured not to be clickable. In the image data converted from the RGB format to the Lab format, when the luminance L is in the vicinity of the values 0 and 100, the chromaticities a and b do not both take a value not less than the predetermined value and not more than the predetermined value. When such a point is clicked, it is made to be within the specified point limit value.

  As a method of drawing a curve, the method of clicking as described above has been described, but instead, by dragging a curve, that is, the mouse body is moved while pressing the button of the mouse 24 on the existing curve. It is good also as a structure which deform | transforms the curve by operation to make. In the case of this configuration, the curve for the desired chromaticity a (or chromaticity b) can be transformed without switching the radio buttons RB1 and RB2. Note that a curve can be created and deformed by both clicking and dragging.

  Returning to FIG. 3, when the adjustment amount designation dialog box DB is displayed in step S100, the CPU 11 performs a process of receiving an instruction from the mouse 24 for the graph GH (step S120). The “instruction” here is a command received by a click (or drag) operation for drawing the curves C1 and C2. Next, the CPU 11 performs a process of drawing the curve C1 (or C2) on the graph GH based on the received instruction from the mouse 24 (step S130). As described above, when the right radio button RB1 is in the selected state, the curve C1 for the chromaticity a is drawn, and when the left radio button RB2 is in the selected state, the curve for the chromaticity b. Draw C2.

  Next, the CPU 11 calculates an increase / decrease value Δa (L) of the chromaticity a for each value 0-100 of the luminance L from the curve C1, and an increase / decrease value Δb of the chromaticity b for each value 0-100 of the luminance L from the curve C2. A process of calculating (L) is performed (step S140). The increase / decrease values Δa (L) and Δb (L) are stored in the memory 13 in the form of a table.

  FIG. 8 is an explanatory diagram showing an example of the table data TBL representing the increase / decrease values Δa (L) and Δb (L) of the chromaticities a and b with respect to each value 0 to 100 of the luminance L. As shown in the figure, the table data TBL is arranged such that the luminance L is vertically arranged from a value of 0 to 100, and an increase / decrease value Δa of the chromaticity a and an increase / decrease value Δb of the chromaticity b with respect to each value of the luminance L. They are arranged in rows. In step S140, the increase / decrease value Δa of chromaticity a is obtained from the curve C1, and these values are stored in the second column, and the increase / decrease value Δb of chromaticity b is obtained from the curve C2, and these values are obtained. Stored in the third column. In addition, it is not necessarily limited to data in such a table format, and instead of this configuration, map data in which the curves C1 and C2 are mapped as they are can be used.

  Thereafter, the CPU 11 executes a chromaticity correction routine for correcting the chromaticity of the original image data Dp based on the increase / decrease values Δa (L) and Δb (L) obtained in step S130 (step S150). Details of this chromaticity correction routine will be described later.

  Thereafter, the CPU 11 performs processing for changing the image displayed in the work field FDW from the original image data Dp to the corrected image data Dp ′ after the chromaticity correction in step S150 (step S160). Subsequently, the CPU 11 performs a process of determining whether or not the chromaticity correction performed in step S150 is appropriate based on an instruction from the operator (step S170). Specifically, the above determination is made based on whether or not the [execute] button BT11 (FIG. 4) provided in the adjustment amount designation dialog box DB is clicked by the operator. The operator can determine whether the chromaticity correction is appropriate by viewing the corrected image data Dp ′ displayed in the work field FDW.

  If the “execute” button BT11 is clicked and the determination is affirmative, the process proceeds to step S180. On the other hand, if a negative determination is made in step S170, that is, if the [Execute] button BT31 is not clicked and a new instruction is given to the graph GH, the process returns to step S120, and steps S120 to S170 are performed. Repeat the process.

  In step S180, the CPU 11 performs processing for storing the corrected image data Dp ′ after the chromaticity correction in step S140 as color adjusted image data XDp in a predetermined holder prepared in the hard disk drive 15. Thereafter, the process returns to “RETURN” to end the color adjustment processing routine.

  The chromaticity correction routine executed in step S150 will be described in detail below. FIG. 9 is a flowchart showing details of the chromaticity correction routine. When the process proceeds to this chromaticity correction routine, as shown in the figure, the CPU 11 first sets a value 0 to a variable i indicating the horizontal position of the original image data Dp (step S210), and then the original image data. A value 0 is set to the variable j indicating the vertical position of Dp (step S220). Subsequently, the CPU 11 selects pixel data P (i, j) at coordinates (i, j) determined by the variables i and j from the original image data Dp, and this pixel data P (i, j). The RGB values are read out, and then the RGB values are converted into Lab values (step S230).

  In order to convert from device-dependent colors such as RGB (device-dependent color) to devices such as Lab, which do not depend on devices (device-independent color), it is necessary to grasp the characteristics of the color representation of the device. In this computer system, a profile describing characteristics of color expression of the device (in this embodiment, the digital camera 26 is applicable) is stored in the memory 13 in advance. In step S230, although detailed description is omitted here, a process of converting RGB format pixel data into Lab format pixel data is performed using a known method using the profile. The Lab values obtained in this way are L1, a1, and b1 here.

  Thereafter, the CPU 11 compares the luminance L1 obtained in step S230 with the table data TBL of the increase / decrease values Δa (L) and Δb (L) obtained in step S130 in FIG. (L1) and Δb (L1) are obtained and added to the chromaticities a1 and b1 obtained in step S230, respectively (step S240). That is, addition processing based on the following expressions (1) and (2) is performed.

a1 ′ = a1 + Δa (L1) (1)
b1 ′ = b1 + Δb (L1) (2)

  Thereafter, the CPU 11 obtains the luminance L1 obtained in step S230, the new chromaticity a1 obtained in step S240 (= a1 ′ in equation (1)), and the new chromaticity b1 obtained in step S240. A process of converting the Lab value consisting of (= b1 ′ in equation (2)) into an RGB value is performed (step S250). The memory 13 stores in advance a profile describing the characteristics of the color expression of the display 20, but in step S250, the Lab format pixel data is converted into RGB format pixel data using the display 20 profile. Perform processing.

  Subsequently, the CPU 11 stores the RGB value obtained in step S280 as the pixel data Pout (i, j) of the new corrected image data Dp ′ (step S260). Thereafter, the CPU 11 increments the variable j by a value 1 (step S270), and determines whether or not the variable j exceeds the number of pixels n in the vertical direction of the original image data Dp (step S280). If it is determined that the variable j does not exceed n, the CPU 11 returns the process to step S230 and repeatedly executes the processes of steps S230 to S280.

  On the other hand, if it is determined in step S280 that the variable j has exceeded n, the process proceeds to step S290. In step S290, the variable i is incremented by 1 and then it is determined whether or not the variable i exceeds the number of pixels m in the horizontal direction of the original image data Dp (step S300). If it is determined that the variable i does not exceed m, the CPU 11 returns the process to step S220, and repeatedly executes the processes of steps S220 to S300. On the other hand, if it is determined in step S300 that the variable i has exceeded m, it is determined that the corrected image data Dp ′ has been obtained, and the process returns to “RETURN”, and the chromaticity correction routine is temporarily terminated.

  The process of fetching the original image data Dp from the hard disk drive 15 by clicking the [Input] button BT1 and the process of step S230 of the color adjustment process correspond to the image data input unit 31 (FIG. 1). In other words, after the original image data Dp in the RGB format is captured, the pixel data P (i, j) of the original image data Dp is read out and converted into Lab values, thereby converting the target image data in the Lab format. The configuration of the input image data input unit 31 is realized. Of the adjustment amount designation dialog box and the color adjustment process, steps S120 to S140 correspond to the adjustment amount designation unit 32 (FIG. 1), and steps S150 (steps S210 to S240, S270 to S300). Corresponds to the image data correction unit 33 (FIG. 1), and the processing in steps S250 and S160 corresponds to the image data output unit 34 (FIG. 1).

C. Action / effect:
According to the computer system of the first embodiment configured as described above, the original image data expressed in the RGB format is converted into the Lab format data, and then the luminance L of the Lab value is changed. Without change, the chromaticities a and b are changed by the increase / decrease values Δa (L) and Δb (L) corresponding to the luminance L, and then the luminance L and the chromaticities a and b after the change are formed. The data is converted back to RGB data and output to the display 20 as corrected image data. The increase / decrease values Δa (L) and Δb (L) are designated according to instructions from the operator. Therefore, the operator can adjust the color balance determined from the chromaticities a and b to the favorite color without changing the brightness (luminance L) of the original image data Dp.

  Specifically, the operator looks at the original image data Dp displayed on the display 20 and checks a portion that should originally be displayed as gray. For example, when the portion is reddish, In the graph GH in the adjustment amount designation dialog box DB shown in FIG. 4, a luminance L that is supposed to correspond to the brightness of the location is determined, and an increase / decrease value of the chromaticity (green to red) a corresponding to the luminance L Perform the operation to specify the minus side. As a result, the reddish portion can be made neutral gray by weakening red. In addition, for example, when the portion is bluish, the operator determines a luminance L that is supposed to correspond to the brightness of the portion in the graph GH in the adjustment amount designation dialog box DB, and the luminance L An operation for designating the increase / decrease value of the chromaticity (blue to yellow) b corresponding to to the plus side is performed. As a result, the bluish portion can be made neutral gray by weakening the blue.

  That is, since the operator can change the chromaticities a and b corresponding to the psychological four primary colors of the person, the operator can easily give the intended color to the image. Therefore, according to the computer system of this embodiment, the gray balance can be adjusted with high accuracy and ease. In addition to the gray balance, the color balance for other colors can also be adjusted.

  In addition, when the original image data Dp is a monochrome photographed image, the following effects are also obtained. The color adjustment of a monochrome captured image is generally performed using a color pattern or a color circle, but the correction portion and the correction amount should be different depending on the target image. For example, a high-key image (some parts of the entire photo are brightly flying) and a low-key image (the whole photo is dark and sinking) have different impressions even when the same correction processing is performed. The color correction according to the brightness according to the present embodiment can provide chromaticity correction with a high degree of freedom suitable for the image.

  As a modification of the first embodiment, when an arbitrary position on the original image data Dp displayed in the work field FDW of the application window WD is clicked when the adjustment amount designation dialog box DB is displayed. Then, the RGB value of the pixel at the clicked position is converted into a Lab value, and the brightness L of the converted Lab value is displayed on the horizontal axis of the graph GH displayed in the adjustment amount designation dialog box DB. A corresponding location may be displayed so as to be identifiable by coloring or blinking. According to this configuration, it is possible to easily obtain the luminance L corresponding to the brightness of the location that is checked to be displayed in gray in the specific operation by the operator described above. Therefore, the operability is improved.

2. Second embodiment:
Next, a second embodiment of the present invention will be described. The second embodiment is the same as the first embodiment except for the configuration of the adjustment amount designation dialog box, and the other configurations are the same.

  FIG. 10 is an explanatory diagram showing an example of the adjustment amount designation dialog box DB2 of the second embodiment. As shown in the figure, this adjustment amount designation dialog box DB2 includes the same graph GH, radio buttons RB1, RB2 and [Execute] button BT11 as in the first embodiment, and a plurality of types of sample graphs prepared in advance. SGH1 to SGH3 are provided. These sample graphs SGH1 to SGH3 are preliminarily described curves indicating the relationship between the luminance L and the chromaticities a and b, and are icons for receiving instructions from the operation. When the operator clicks one of the plurality of sample graphs SGH1 to SGH3, the relationship between the luminance L and the chromaticities a and b drawn on the clicked sample graph SGH1 (or SGH2 and SGH3). Can be transferred to the graph GH.

  In this embodiment, a sample graph SGH1 of "intermediate temperature black tone" is displayed at the top, a sample graph SGH2 of "shadow temperature black tone" is displayed at the center, and a sample graph SGH3 of "highlight temperature black tone" is displayed at the bottom. Are provided. The operator only needs to click on the sample graph SGH2 to make the shadow portion warm and black, and the same applies to the halftone portion and the highlight portion. Therefore, according to this embodiment, the operability is excellent, and the gray balance can be adjusted more easily. Further, in this embodiment, since one selected from the plurality of types of sample graphs SGH1 to SGH3 is moved to the graph GH, the operator operates the graph GH. Thus, the color balance can be easily adjusted based on the selected sample graph SGH1 (or SGH2, SGH3).

  As a modification of the second embodiment, the selected sample graph SGH1 (or SGH2) can be selected without moving one selected from the plural types of sample graphs SGH1 to SGH3 to the graph GH. , SGH3), the increase / decrease values Δa (L) and Δb (L) of the chromaticities a and b for the values 0 to 100 of the luminance L may be calculated directly. In this configuration, the adjustment amount designation dialog box does not necessarily require the graph GH, and may be configured without the graph GH.

  As another modification of the second embodiment, the curves C1 and C2 input by the operator to the graph GH can be registered in the memory 13 for the user. According to this configuration, the operator can reuse the favorite color balance adjustment amount input to the graph GH. In this configuration, the sample graphs SGH1 to SGH3 are not necessarily required, and all of them can be registered for the user.

  Furthermore, as another modified example of the second embodiment, instead of a plurality of types of sample graphs SGH1 to SGH3, a character string that can identify each of the sample graphs SGH1 to SGH3, for example, “intermediate temperature control black tone”, It is possible to display a list of each character string of “shadow portion temperature black tone” and “highlight portion temperature black tone” and select one of the displayed character strings by radio buttons or the like. it can. In this configuration, data representing each of the sample graphs SGH1 to SGH3 (for example, the table data shown in FIG. 8) is stored in advance in the memory 13, and data corresponding to the selected character string is stored from the memory 13. Depending on the configuration to be read, increase / decrease values Δa (L) and Δb (L) of chromaticity a and b with respect to each value 0 to 100 of luminance L can be obtained. With this configuration, the operability is excellent and the gray balance can be easily adjusted.

3 . Other embodiments:
The present invention is not limited to the first and second embodiments and modifications described above, and can be carried out in various modes without departing from the gist of the present invention. Various modifications are possible.

(1) In the above embodiment, after the original image data Dp in the RGB format is taken in, one piece of pixel data P (i, j) of the original image data Dp is read out, converted into Lab values, and chromaticity However, instead of this, all the pixel data of the original image data Dp may be first converted to the Lab format and then the chromaticity correction may be performed.

(2) In the above embodiment, the original image data is converted to RGB format data, and the Lab values corresponding to the first to third parameters of the present invention are obtained from the RGB values. The original image data may be image data expressed in the Lab format.

(3) In the above embodiment, the target image data to be subjected to chromaticity correction is Lab format color image data, but instead, the pixel color is expressed by the brightness Y and the color differences Cr and Cb. Alternatively, YCrCb format color image data may be used. That is, after converting the original image data in RGB format into image data in YCrCb format, the adjustment amounts of the color differences Cr and Cb for each value of brightness Y can be specified in accordance with instructions from the operator ( For example, in FIG. 4, the adjustment amount is specified using an adjustment amount specification dialog box in which the luminance L is changed to lightness Y, the chromaticity a is changed to chrominance Cr, and the chromaticity b is changed to chrominance Cb. The YCrCb format image data is corrected in accordance with the adjusted amount, and the corrected image data is returned to the RGB format image data and displayed on the display 20. Also with this configuration, the color balance can be adjusted with high accuracy and ease. Furthermore, the target image data is replaced with the color image data in the YCrCb format, and is in another format in which the color of the pixel is expressed by the first parameter representing brightness and the second and third parameters related to color. It can also be image data.

(4) In the above embodiment, the graph GH provided in the adjustment amount designation dialog box DB shares the ordinate with the chromaticities a and b. Instead, the luminance and chromaticity a It is also possible to use a dialog box including a first graph indicating the correspondence relationship between the luminance and chromaticity B and a second graph indicating the correspondence relationship between the luminance and chromaticity B. Further, the graph GH has a configuration in which the vertical axis is the luminance L and the horizontal axis is the chromaticity a and b, instead of the configuration in which the horizontal axis is the luminance L and the vertical axis is the chromaticity a and b. You can also.

(5) In the embodiment described above, every time the graph GH is changed in the adjustment amount designation dialog box DB, the chromaticity correction of the original image data Dp is performed. Alternatively, the pre-correction image and the post-correction image may be preview-displayed, and actual correction on the original image data Dp may be performed only after the [Execute] button BT11 is clicked.

(6) In the above embodiment, the output device of the present invention is the display 20, but the output device may be the printer 29 instead. Since the printer 29 is a color printer that receives CMYK format color image data, in this modification, the original image data is temporarily replaced with CMY format image data, and the CMY format image data is converted into Lab format image data. Convert to. The handling of the Lab format image data is the same as in the above embodiment, and the Lab format image data after chromaticity correction is converted into a CMYK format image signal and output to the printer 29. According to this configuration, the gray balance of the printed matter from the printer 29 can be easily adjusted with high accuracy.

It is explanatory drawing which shows schematic structure of the computer system to which 1st Example of this invention is applied. It is explanatory drawing which shows an example of application window WD. 4 is a flowchart illustrating color adjustment processing executed by a CPU 11. It is explanatory drawing which shows an example of dialog box DB for adjustment amount designation | designated. It is explanatory drawing which shows an example of operation which designates the adjustment amount about chromaticity a which shows green-red. It is explanatory drawing which shows an example of operation which designates the adjustment amount about chromaticity b which shows blue-yellow. It is explanatory drawing which shows operation which performs a click in multiple times and draws a curve. It is explanatory drawing which shows an example of the table data TBL showing the increase / decrease value (DELTA) a (L) and (DELTA) b (L) of chromaticity ab with respect to each value 0-100 of the brightness | luminance L. FIG. 4 is a flowchart showing details of a chromaticity correction routine executed in the color adjustment processing of FIG. 3. It is explanatory drawing which shows an example of dialog box DB2 for adjustment amount designation | designated of 2nd Example.

Explanation of symbols

10 ... Personal computer 11 ... CPU
12 ... Bus 13 ... Memory 14 ... Display image memory 15 ... Hard disk drive 16 ... Input control unit 17 ... Display control unit 18 ... Output control unit 20 ... Display 22 ... Keyboard 24 ... Mouse 26 ... Digital camera 28 ... CD drive 29 ... Printer 31 ... Image data input part 32 ... Adjustment amount designation part 33 ... Image data correction part 34 ... Image data output unit Dp ... Original image data XDp ... Color adjusted image data Pr ... Computer program DB ... Dialog box for specifying adjustment amount WD ... Application window FDW ... Work field GH ... graph RB1, RB2 ... radio button BT11 ... [execute] button DB2 ... second adjustment amount specification dialog box SGH1-SGH3 ... sample graph

Claims (16)

A color adjustment device for adjusting the color of color image data output from an output device,
Image data input means for inputting target image data in which the color of a pixel is expressed by a first parameter representing brightness and second and third parameters relating to color;
Adjustment amount designating means for designating respective adjustment amounts of the second and third parameters for each value of the first parameter according to an instruction from an operator;
Adjustment amount storage means for storing each adjustment amount designated by the adjustment amount designation means in association with the value of the first parameter;
For each pixel of the target image data, the adjustment amount corresponding to the value of the first parameter of the pixel is obtained by collating with the storage content of the adjustment amount storage means, and the second of the pixel is included. Image data correction means for correcting the value of the third parameter based on each of the obtained adjustment amounts ;
A color adjustment apparatus comprising: image data output means that converts target image data corrected by the image data correction means into color image data expressed by a color space that can be reproduced by the output apparatus and sends the color image data to the output apparatus. The color adjustment device according to claim 1,
The target image data includes luminance L as the first parameter, chromaticity a from green to red as the second parameter, and chromaticity b from blue to yellow as the third parameter. A color adjusting device which is Lab format color image data in which the color of a pixel is expressed by. The color adjustment device according to claim 1,
The target image data is color image data in YCrCb format in which the color of a pixel is expressed by lightness Y as the first parameter and color differences Cr and Cb as the second and third parameters. apparatus. The color adjusting device according to any one of claims 1 to 3,
The adjustment amount designation means includes:
By taking the first parameter on one of the horizontal axis and the vertical axis and taking the respective adjustment amounts of the second and third parameters on the other axis, the first parameter and the second, second, Display control means for displaying on a display device a graph representing the relationship between each of the three parameter adjustment amounts;
A graph change that accepts an instruction from the operator for the displayed graph and changes the relationship between the adjustment amounts of the first parameter and the second and third parameters shown in the graph according to the instruction from the operator And a color adjusting device. The color adjusting device according to any one of claims 1 to 3,
The adjustment amount designation means includes:
Storage means for storing in advance a plurality of types of parameter correlation data indicating the relationship between the first parameter and the adjustment amounts of the second and third parameters;
A color adjustment apparatus comprising: selection means for designating the adjustment amount by selecting one of a plurality of types of parameter correlation data stored in the storage means based on an instruction from an operator . The color adjustment device according to claim 5,
The adjustment amount specifying means further includes:
Display control means for reading the plurality of types of parameter correlation data from the storage means and displaying a plurality of graphs respectively representing the parameter correlation data on a display device;
The selection means includes
A graph selecting means for selecting one of the plurality of types of graphs based on an instruction from an operator;
A color adjustment apparatus comprising: parameter association data selection means for selecting the parameter association data corresponding to the selected graph. The color adjusting device according to any one of claims 1 to 6,
The output device is a color display;
The color image data is a color adjustment device in which the color of a pixel is expressed by three primary colors of red, green, and blue. The color adjustment device according to claim 7,
The target image data input means includes
Original image data input means for inputting original image data in which the color of a pixel is expressed by the three primary colors of red, green, and blue;
The original image data is converted into color image data in which the color of a pixel is expressed by a first parameter representing brightness and second and third parameters relating to color, and the converted color image data is converted into color image data. A color adjustment apparatus comprising: original image data conversion means for obtaining the target image data. A color adjustment method for adjusting the color of color image data output from an output device,
Input target image data in which the color of the pixel is expressed by the first parameter representing brightness and the second and third parameters relating to the color ;
Specify the respective adjustment amounts of the second and third parameters for each value of the first parameter according to instructions from the operator ,
Storing each of the designated adjustment amounts in a memory in association with the value of the first parameter;
For each pixel of the target image data, the adjustment amount corresponding to the value of the first parameter of the pixel is obtained by collating with the storage content of the memory, and the second and third of the pixel are obtained. The value of the parameter is corrected based on each of the obtained adjustment amounts ,
A color adjustment method in which the corrected target image data is converted into color image data expressed by a color space reproducible by the output device and sent to the output device. A computer program for adjusting the color of color image data output from an output device,
A function of inputting target image data in which the color of a pixel is expressed by a first parameter representing brightness and second and third parameters relating to color;
A function of designating respective adjustment amounts of the second and third parameters for each value of the first parameter according to an instruction from an operator;
A function of storing each designated adjustment amount in a memory in association with a value of the first parameter;
For each pixel of the target image data, the adjustment amount corresponding to the value of the first parameter of the pixel is obtained by collating with the storage content of the memory, and the second and third of the pixel are obtained. A function of correcting the value of the parameter based on each of the obtained adjustment amounts ;
A computer program for causing a computer to realize a function of converting the corrected target image data into color image data expressed by a color space reproducible by the output device and sending the color image data to the output device.

A computer program according to claim 10,
The target image data includes luminance L as the first parameter, chromaticity a from green to red as the second parameter, and chromaticity b from blue to yellow as the third parameter. A computer program which is color image data in the Lab format in which the color of a pixel is expressed by. A computer program according to claim 10,
The target image data is color image data in YCrCb format in which pixel colors are expressed by brightness Y as the first parameter and color differences Cr and Cb as the second and third parameters. . A computer program according to any one of claims 10 to 12,
The function to specify the adjustment amount is
By taking the first parameter on one of the horizontal axis and the vertical axis and taking the respective adjustment amounts of the second and third parameters on the other axis, the first parameter and the second, second, A function for displaying on a display device a graph representing the relationship between each of the three parameter adjustment amounts;
A function of receiving an instruction from the operator for the displayed graph and changing a relationship between the first parameter and the adjustment amounts of the second and third parameters shown in the graph according to the instruction from the operator; A computer program comprising: A computer program according to any one of claims 10 to 12,
The function to specify the adjustment amount is
A function for storing in advance a plurality of types of parameter correlation data indicating the relationship between the first parameter and the adjustment amounts of the second and third parameters;
A computer program comprising a function for designating the adjustment amount by selecting one of the plurality of types of parameter correlation data based on an instruction from an operator. A computer program according to claim 14, comprising:
The function of specifying the adjustment amount is further
A function of displaying a plurality of graphs respectively representing the plurality of types of parameter correlation data on a display device;
The function of selecting the one parameter correlation data is as follows:
A function of selecting one of the plurality of types of graphs based on an instruction from an operator;
A computer program comprising: a function of selecting the parameter correlation data corresponding to the selected graph.   A computer-readable recording medium on which the computer program according to any one of claims 10 to 15 is recorded.

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